depends if you fit the venturi nozzle on the powerhead, its very quiet without it, with it fitted you get a slight bubbling noise. The filter on those aquanano tanks is built in to a partitioned off section in the back of the tank, and the water is pumped round with a conventional powerhead rather than having a normal internal canister filter. This means you can fit loads of biomedia in there and it has a compartment for the heater hidden at the back as well which means less clutter in the tank and the fish can't hurt themselves on it.